JP2657438B2 - Primer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a primer composition which is effective for imparting adhesion to a condensation reaction type silicone rubber.

[0002]

2. Description of the Related Art In recent years, with the expanding use of silicone rubber, it has been required to bond the silicone rubber to various substrates such as metal or synthetic resin. Conventionally, there has been known a method of imparting self-adhesion by adding a carbon functional silane (silane coupling agent) such as aminosilane as an adhesion aid in order to impart adhesiveness to a condensation reaction type silicone rubber. This method improves the adhesiveness, but causes inconveniences such as a decrease in surface releasability and an increase in rubber hardness during heating.

[0003] Further, a method of bonding using a primer composition or the like obtained by mixing carbon functional silane and a titanium organic acid salt is also known. However, the conventional primer composition has, for example, adhesion durability to a portion where a large strain is applied between the substrate and the silicone rubber, such as between a roll core of a copying machine roll and a surface silicone rubber. Not enough.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a highly durable primer composition for use in bonding a condensation reaction type silicone rubber to various substrates such as metal or synthetic resin. It is in.

[0005]

According to the present invention, there is provided (A) a compound having at least two alkenyl groups in one molecule.
Organopolysiloxane, (B) The number of hydrogen atoms bonded to silicon atoms in one molecule is small.
Organohydrogen polysiloxane having at least two
NThe component (A)
Alkenyl group contained in the organopolysiloxane
To the silicon atoms contained in component (B) with respect to the total amount of
An amount such that the combined hydrogen atoms become 1.0 to 20.0 mole times, (C) Platinum catalystTo the total amount of component (A) and component (B)
The amount of which is 0.1 to 500 ppm,And (D) average unit formula: R¹ _aX_bSiO_{(4-ab) / 2}  (Where R¹Is a substituted or unsubstituted monovalent hydrocarbon group
And acryloxyl, methacryloxyl or epoxy
X is a hydrolyzable group; a is 0
≦ a ≦2, B are represented by 2 ≦ b ≦ 4 and 2 ≦ a + b ≦ 4
Which is bonded to a silicon atom in one molecule.
Organosilicon compounds having at least two hydrolyzable groups
Stuff(A) For 100 parts by weight of component
5 to 50 parts by weight,Providing a primer composition comprising:
Is to do.

(A) Organopolysiloxane The organopolysiloxane which is the component (A) of the primer composition of the present invention has at least two alkenyl groups in one molecule.
Having a viscosity at 25 ° C. of preferably 50 to 200,000 cS
t, more preferably in the range of 100 to 100,000 cSt. Examples of the alkenyl group include a vinyl group,
An alkenyl group having 2 to 8 carbon atoms, such as an allyl group, a 1-methyl-2-propenyl group, a hexenyl group, a γ-acryloxypropyl group and a γ-methacryloxypropyl group, and preferably a vinyl group can be exemplified. . Further, as an organic group other than an alkenyl group, for example, a methyl group, an ethyl group,
Alkyl groups such as propyl group and butyl group; aryl groups such as phenyl group and tolyl group; aralkyl groups such as benzyl group and β-phenylethyl group; substituting some or all of the hydrogen atoms of these groups with halogen atoms and the like Or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, such as a substituted chloromethyl group and a 3,3,3-trifluoropropyl group.

As such an organopolysiloxane,
Specifically, the following chemical formula:

Embedded image (In the above formula, p is 2 or 3, s, u and w are positive integers, t, v and x are 0 or positive integers, and s +
t, u + v and w + x each represent a positive integer of 2000 or less. )) Is exemplified. The structure of the organopolysiloxane as the component (A) may be a linear or partially branched structure. The organopolysiloxane may be used alone or as a mixture of two or more.

(B) Organohydrogenpolysiloxane The organohydrogenpolysiloxane which is the component (B) of the primer composition of the present invention has at least two hydrogen atoms bonded to a silicon atom in one molecule. It acts as a crosslinking agent for the organopolysiloxane (A). The organohydrogenpolysiloxane of the component (B) may have an organic group bonded to a silicon atom,
The same as the organic group other than the alkenyl group in the organopolysiloxane of the component (A) can be mentioned.
As the organohydrogensiloxane of the component (B), for example, the following general formula:

Embedded image (In the above formula, b, c, d, e, f, g and i represent 0 or a positive integer, h represents an integer of 2 or more, and the number of silicon atoms in the molecule is usually 400 or less. .)

Embedded image (In the above formula, R ² is a hydrogen atom, a methyl group, a propyl group,
Or a trimethylsiloxy group. ) And the like.

The structure of the organohydrogenpolysiloxane as the component (B) may be any of linear, branched, cyclic and three-dimensional network structures, and may be a mixture thereof. The amount of the organohydrogenpolysiloxane used as the component (B) is determined based on the total amount of alkenyl groups contained in the organopolysiloxane used as the component (A). atom is an amount to be 1.0 to 20.0 mol times, and more preferably in an amount to be 1.2 to 10.0 mol per mol.

(C) Platinum Catalyst The platinum catalyst which is the component (C) of the primer composition of the present invention is a catalyst for an addition reaction and acts as a curing accelerator.
Examples of such a catalyst include, but are not limited to, platinum black, alumina, those in which solid platinum is supported on a carrier such as silica, chloroplatinic acid, alcohol-modified chloroplatinic acid, chloroplatinic acid and an olefin. And a complex of platinum and vinyl siloxane.

When the catalyst is a solid, it is preferable to use a finely ground one or a carrier having a small particle size and a large specific surface area in order to improve dispersibility. Also, chloroplatinic acid or a complex of chloroplatinic acid and an olefin is
It is desirable to use these by dissolving them in a solvent such as alcohol, ketone, ether or hydrocarbon. The amount of these catalysts can be used to obtain a desired curing rate with a so-called catalyst amount. However, in order to obtain an economical viewpoint or a good cured product, the total amount of the component ( A) and the component (B) must be reduced. On the other hand, it is in the range of 0.1 to 500 ppm. More specifically, those which are compatible with the siloxane component, such as alcohol-modified or siloxane-modified chloroplatinic acid, are used in an amount of 0.1-0.1% based on the total amount of the components (A) and (B).
The solid catalyst such as 100 ppm (in terms of platinum) and platinum black is preferably in the range of 20 to 500 ppm (in terms of platinum).

(D) Organosilicon compound The organosilicon compound, which is the component (D) of the primer composition of the present invention, is represented by the above-mentioned average unit formula, and is a hydrolyzable compound bonded to a silicon atom in one molecule. It has at least two groups. This component (D) acts on the bonding and adhesion between the primer composition of the present invention and the condensation reaction type silicone rubber.

R ¹ in the formula is, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group and a hexyl group; a cyclohexyl group; an alkenyl group such as a vinyl group and an allyl group; An aryl group such as a group; an aralkyl group such as a benzyl group and a phenylethyl group; Formulas which are monovalent hydrocarbon groups and acryloxyl, methacryloxy or epoxy group-containing groups, exemplified by those of from 1 to 10, preferably 1 to 8:

Embedded image And the like.

X represents a hydrolyzable group, for example, an alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, a methoxyethoxy group and an ethoxyethoxy group, an acyloxy group such as an acetoxy group, a propionoxy group and a butyryloxy group; Examples thereof include alkenyloxy groups such as an isopropenyloxy group, an isobutenyloxy group, a 1-ethyl-2-methylvinyloxy group, and a 1-methylvinyloxy group.

Specific examples of such organosilicon compounds include methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, tetraethoxysilane, tetrapropoxysilane, methyltriacetoxysilane, vinyltris (1-methylvinyloxy ) Silane, vinyltris (β-methoxyethoxy) silane, γ
-Methacryloxypropyltrimethoxysilane, γ-acryloxypropyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxy Examples thereof include silane and the like, and one or more partially hydrolyzed condensates thereof. The amount of component (D) used is (A) 100
The amount is 5 to 50 parts by weight, more preferably 1 to 50 parts by weight.
0 to 30 parts by weight.

Other Additives The primer composition of the present invention comprises the above (A), (B), (C) and
It is obtained by uniformly mixing the component (D). The primer composition of the present invention can be used after being diluted with an organic solvent, if necessary, for example, in order to facilitate the application of the primer composition. As the organic solvent, for example, toluene, xylene, benzene, heptane,
Hexane, trichloroethylene, perfluoroethylene,
Ethyl acetate, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, tetrahydrofuran, ligroin, rubber volatile oil and the like can be mentioned, and are appropriately selected in consideration of the volatility during the coating operation.

The primer composition of the present invention may further comprise a silica filler and RSiO _3/2 (where R represents 1 to 10 carbon atoms, preferably 1 to 10 carbon atoms) in order to improve the film strength upon curing.
6 unsubstituted or substituted monovalent hydrocarbon groups), SiO _4/2 units and the like; silicone resins for improving heat resistance, cerium oxide, cerium hydroxide, cerium fatty acid salts, iron fatty acid salts, Titanium oxide, carbon black, etc .; known additives such as various pigments can be added for coloring. These additives can be arbitrarily added as long as the desired properties of the composition of the present invention are not impaired.

Further, it is preferable to add an adhesion aid to the composition of the present invention, whereby the shear adhesive strength is further improved. As an adhesion aid, for example,
Compounds having an alkoxysiloxy group disclosed in JP-B-53-21026, compounds having an epoxy-containing hydrocarbon group disclosed in JP-B-53-13508, and alkoxy-siloxy groups and epoxy-containing compounds disclosed in JP-B-59-5219. A compound having a hydrocarbon group is preferably used. More specifically, but not exclusively, the following chemical formula:

Embedded image The organic silicon compound represented by these is illustrated. Further, these can be used by appropriately increasing the degree of polymerization according to the use. The amount of the adhesion aid used is usually 0.5 parts per 100 parts by weight of the organopolysiloxane (A).
The amount may be up to 20 parts by weight, particularly preferably 1 to 10 parts by weight.

Furthermore, in order to further improve the adhesiveness, for example, triallyl isocyanurate, triallyl trimellitate or a compound obtained by modifying these with siloxane can be added to the composition of the present invention. More specifically, for example, the following chemical formula:

Embedded image

Embedded image

Embedded image

Embedded image Are represented. The amount of the compound used is not particularly limited, but is usually about 0.5 to 3 parts by weight based on 100 parts by weight of the organopolysiloxane (A).

[0020] Applications in the case of bonding the silicone rubber to a substrate by using the primer composition of the present invention, after applying the primer composition of the present invention to a substrate, for example, 15 minutes or more, dried preferably 30 to 120 minutes air After the solvent is evaporated, the primer composition of the present invention is cured by heating, for example, at 100 to 180 ° C. for 10 to 120 minutes to form a flexible primer composition on the substrate. It is preferable to bond a condensation reaction type silicone rubber.

The material of the substrate to which the composition of the present invention can be applied is not particularly limited. For example, iron, aluminum, nickel,
Metals such as chromium, zinc or copper or alloys thereof,
Synthetic resins such as phenolic resins and epoxy resins are exemplified.

The primer composition of the present invention is effective for bonding silicone rubber to various kinds of substrates, and can be used for various purposes. Particularly, it is very effective in bonding industrial rolls for forming plastic films that are exposed to high temperatures for a long period of time or industrial rolls that perform corona discharge treatment on surfaces of polyethylene films or the like in which high temperature and other shearing stress are applied to the bonding interface. .

[0023]

EXAMPLE 1 In a stainless steel container, a general formula:

Embedded image Dimethylpolysiloxane having a viscosity of 100,000 cSt (25 ° C) and trivinylsilyl groups at both ends.
00 parts by weight, 0.05 part by weight of an octanol solution of chloroplatinic acid (Pt: 2% by weight) and 3-methyl-3-hydroxy-1
-After adding 0.05 parts by weight of butyne and mixing uniformly, the formula:

Embedded image Is obtained by adding 3.5 parts by weight of an organohydrogenpolysiloxane having hydrogen atoms bonded to 10 silicon atoms represented by and uniformly mixing, and further partially hydrolyzing 100 parts by weight of toluene and tetraethoxysilane. 15 parts by weight of ethyl polysilicate (containing 40% SiO ₂ ) containing an average of 12 ethoxy groups in one molecule was added and mixed to obtain a composition. This composition is referred to as Primer A.

Apply Primer A to an aluminum plate,
After heating at 30 ° C for 30 minutes, a condensation reaction type RTV silicone rubber KE21 (Shin-Etsu Chemical Co., Ltd., hardness: 70) is sandwiched between and cured at 25 ° C for 3 days. A body was prepared, and a load was applied in the direction of 6 in FIG. 1 to perform a shear adhesion measurement test. Table 1 shows the results. After baking primer A on the surface of an aluminum core and an iron core having a diameter of 30 mm, the RTV silicone rubber KE21 was cured at room temperature to a thickness of 10 mm to prepare a roll-shaped test body. The two rolls were compressed and arranged in parallel so that the center distance between them became 47 mm as shown in FIG. 2, and rotated at 50 rpm to perform a roll durability test. Table 1 shows the results.

Example 2 In the production of the primer A in Example 1, fumed silica surface-treated with a trimethylsilyl group (specific surface area 3
00m ² / g), except that 15 parts by weight are added and mixed prior to addition of the organohydrogenpolysiloxane Example 1
In the same manner as in the above, a composition was obtained. Primer B
And For the primer B, a specimen was prepared in the same manner as in Example 1, and a shear adhesion measurement and a roll durability test were performed. Table 1 shows the results.

Comparative Example 1 In the primer B of Example 2, 15 parts by weight of ethyl polysilicate containing an average of 12 ethoxy groups in one molecule obtained by partially hydrolyzing tetraethoxysilane was not added. The composition is referred to as Primer C. With respect to the primer C, a specimen was prepared in the same manner as in Example 1, and the shear adhesion measurement and the roll durability test were performed. Table 1 shows the results.

[Table 1]

Example 3 100 parts by weight of dimethylpolysiloxane having a viscosity of 30,000 cSt (25 ° C.) and trivinylsilyl groups at both ends, and 17 parts by weight of fumed silica surface-treated with trimethylsilyl group (specific surface area: 300 m ² / g) And 0.07 parts by weight of octanol solution of chloroplatinic acid (Pt: 2% by weight), 0.08 parts by weight of ethylenecyclohexanol and 1.0 part by weight of triallyl trimellitate, and uniformly mixed.

Embedded image 2.5 parts by weight of a hydrogenpolysiloxane having a hydrogen atom bonded to five silicon atoms represented by the following formula:

Embedded image 3.0 parts by weight of the compound represented by the formula are added and mixed, and 100 parts by weight of toluene, 2.0 parts by weight of allyltrimethoxysilane and 5.0 parts by weight of vinyltrimethoxysilane are further added and uniformly mixed. Thus, a primer composition was obtained. This composition is referred to as Primer D.

Apply primer D to various substrates,
After heating and baking for 30 minutes at room temperature, a condensation test type RTV silicone rubber KE20 (manufactured by Shin-Etsu Chemical Co., Ltd., hardness 55) is cured at room temperature for 3 days to prepare a test specimen, and a measurement test for shear adhesive strength Was done. Table 2 shows the results. In addition, the shear adhesion test specimen was subjected to about 50 displacements at ± 2 mm in the longitudinal direction of FIG. Table 2 shows the results.

Comparative Example 2 A shear adhesive force was obtained in the same manner as in Example 3 using a conventional primer composition for a condensation reaction type silicone rubber (carbon functional silane-titanium organic acid salt system manufactured by Shin-Etsu Chemical Co., Ltd.). And an endurance test. Table 2 shows the results.

[Table 2]

[0030]

Industrial Applicability The primer composition of the present invention is effective for bonding various types of substrates to a condensation-reactive silicone rubber, and has sufficient adhesion even under severe conditions such as high temperature and high shear stress. Power can be maintained. Especially,
The hardness of the rubber is JIS-A among the condensation reaction type silicone rubbers.
It shows durability against high shear stress for those with 40 or more.

[Brief description of the drawings]

FIG. 1 is a perspective view of a test piece used in a shear adhesion measurement test using a primer composition of the present invention.

FIG. 2 is a cross-sectional view of a test piece used for a roll durability test using the primer composition of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Iron core 2 Aluminum core 3 KE21 4 Primer composition 5 Aluminum plate 6 Direction in which load was applied

Claims (1)

(57) [Claims] (A) An alkenyl group is reduced in one molecule.
(B) one molecule having at least two hydrogen atoms bonded to silicon atoms in one molecule.
Organohydrogen polysiloxane having at least two
NThe component (A)
Alkenyl group contained in the organopolysiloxane
To the silicon atoms contained in component (B) with respect to the total amount of
An amount such that the combined hydrogen atoms become 1.0 to 20.0 mole times, (C) Platinum catalystTo the total amount of component (A) and component (B)
The amount of which is 0.1 to 500 ppm,And (D) average unit formula: R¹ _aX_bSiO_{(4-ab) / 2}  (Where R¹Is a substituted or unsubstituted monovalent hydrocarbon group
And acryloxyl, methacryloxyl or epoxy
X is a hydrolyzable group; a is 0
≦ a ≦2, B are represented by 2 ≦ b ≦ 4 and 2 ≦ a + b ≦ 4
Which is bonded to a silicon atom in one molecule.
Organosilicon compounds having at least two hydrolyzable groups
Stuff(A) For 100 parts by weight of component
5 to 50 parts by weight,A primer composition comprising: